One of the crucial questions being brought into focus by recent work on the mechanism of steroid hormone action relates to the function of 8-9 S steroid receptor forms. Stabilization of the 8S receptor at physiological salt concentrations by several groups suggests that this ubiquitous 8S form likely has a role in steroid hormone action. We stand now on the brink of determining the physiological significance of the 8S androgen receptor complex since we have identified a macromolecule (8S androgen receptor-promoting factor, 8S-PF) that converts the native 4.5 S androgen receptor to the 8S complex. Our data indicate that the factor is a protein limited to tissues containing the androgen receptor. I will seek to establish the role of this factor in relation to that of the androgen receptor. My plan is to purify the androgen receptor and prepare an antibody. Receptor antibody will be used as an affinity matrix for purification of 8S-PF. With specific antisera to the androgen receptor and 8S-PF, immunochemical methods will be used to determine their intracellular distributions during development and following hormone withdrawal and treatment. A receptor antibody will give us a handle on studying the steroid- free receptor and provide another means to assess the role of the 8S androgen receptor- promoting factor in the process of nuclear uptake of "activation" of the purified receptor. An antibody to the androgen receptor will also facilitate studies on the nuclear retention and recycling of receptor. I will test the hypothesis that the 8S-promoting factor is a regulatory element in steroid hormone action by determining its effect on steroid and DNA binding properties of the receptor, its influence on nuclear uptake and its interaction with specific components of chromatin in relation to activation of the prostatein genes. In these studies, I expect to help determine how androgens regulate gene expression through a mechanism involving the receptor.